Gabriella Novinda, Gregoria Illya

EVALUASI DOSIS FOTON PADA PASIEN KANKER REKTUM DENGAN TEKNIK 3DCRT DAN IMRT

Introduction

Evaluasi dosis foton pada pasien kanker rektum dengan teknik 3dcrt dan imrt. Evaluasi dosis foton pada pasien kanker rektum menggunakan teknik radioterapi 3DCRT dan IMRT. Studi ini menganalisis distribusi dosis dan dosis ke organ sehat. Temukan metode terbaik.

Abstract

Rectal cancer is one of the deadliest cancers in Indonesia. Treatment of rectal cancer is often done with radiotherapy. External radiotherapy of rectal cancer uses linac which has several methods of irradiation. This study aims to determine the distribution of photon doses through the Conformity Index (CI) and Homogeneity Index (HI) values as well as the doses received by healthy tissue around cancer tissue. This study also aims to find out better methods of external radiotherapy. Making treatment planning using Xi-O TPS software. This study on the 3DCRT method produced HI values of 0.084 ± 0.017 and CI values of 0.98 ± 0.02. In the IMRT method, the HI value is 0.099 ± 0.028 and the CI value is 0.96 ± 0.03. Based on HI and CI analysis, it was found that the 3DCRT method was better than IMRT in the treatment of rectal cancer but not significantly. Meanwhile, the IMRT bowel bag method has a lower average dose compared to the 3DCRT method and the results are significant. In bladder and femoral tissues, the IMRT method is better than the 3DCRT method but is not significant. In rectal cancer, the IMRT technique is better because it can minimize the dose of OAR.

Review

The study presents a valuable dosimetric comparison between 3D Conformal Radiotherapy (3DCRT) and Intensity-Modulated Radiotherapy (IMRT) techniques for rectal cancer patients. Given the high mortality rate of rectal cancer in Indonesia, optimizing radiotherapy protocols is crucial for improving patient outcomes and reducing treatment-related toxicities. The primary objective of this research was to evaluate photon dose distribution within the target volume using Conformity Index (CI) and Homogeneity Index (HI), as well as assessing the doses received by surrounding healthy organs-at-risk (OARs), with the aim of identifying a superior external radiotherapy method. The investigation utilized the Xi-O Treatment Planning System (TPS) software for plan generation and analysis. The findings reveal a nuanced picture regarding the dosimetric advantages of each technique. For target volume coverage, 3DCRT demonstrated slightly better HI (0.084 ± 0.017) and CI (0.98 ± 0.02) values compared to IMRT (HI = 0.099 ± 0.028, CI = 0.96 ± 0.03), though this difference was reported as not statistically significant. A key strength of the IMRT technique, however, emerged in its ability to spare critical OARs. Notably, IMRT delivered a significantly lower average dose to the bowel bag compared to 3DCRT. Furthermore, IMRT also showed an advantage in reducing doses to the bladder and femoral tissues, albeit without reaching statistical significance. The study therefore concludes that, despite marginal differences in target coverage indices, IMRT is ultimately the preferred technique due to its superior capacity to minimize OAR doses, a critical factor in reducing treatment-related toxicities. While the study offers useful insights into treatment planning dosimetrics, several aspects could enhance its impact and generalizability. The abstract's brief mention of "not significantly" for certain comparisons warrants a more detailed statistical analysis to robustly support the conclusions. Crucially, the abstract lacks information regarding the number of patient cases included in this planning study, which limits the interpretation of the presented average values and standard deviations. Future research would benefit from evaluating a larger, more diverse patient cohort. Additionally, exploring other dosimetric parameters for OARs, such as maximum dose or specific dose-volume histogram metrics, could provide a more comprehensive assessment of tissue sparing. Finally, while a planning study provides foundational data, correlating these dosimetric findings with actual clinical outcomes and toxicity rates in patients would be the ultimate step in validating the superiority of one technique over the other.

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